The rotary lawnmower has long been recognized as a hazard to persons who operate it because of the heavy cutter blade which rotates at a relatively high speed, even if the engine is idling. There have been a number of patents issued showing various combinations for reducing the hazard.
U.S. Pat. No. 3,228,177 to Coates shows a rotary mower having a hand control on the handle which must be held in an operative position by the operator while the mower is in use, this control releasing a brake band which is normally held in applied position by a tension spring. When the brake is held OFF, the engine and blade can rotate, but when the hand control is released, the brake is applied by a spring to the shaft, and an electrical contact cooperating with the brake mechanism short-circuits the ignition of the engine. Thus, the engine must be restarted each time the hand control is released by the operator.
U.S. Pat. No. 3,253,391 to Meldahl, U.S. Pat. No. 4,035,994 to Hoff and U.S. Pat. No. 4,044,533 to Wick all show the combination of a centrifugal clutch and a cooperating brake mechanism, whereby when the engine is at idle speed the clutch is disengaged and the brake is applied, thereby dis-engaging the cutter blade from the engine shaft and applying a brake to a member carrying the cutter blade so that it stops rotating. The patents to Meldahl and to Hoff show interconnected throttle and brake mechanisms whereby the throttle and the brake are operated in unison when a manual control is released.
The present invention is of the same general type, combining a brake, a throttle, and a decoupling clutch all of which operate in unison to stop the blade as soon as a manual control is released, without at the same time requiring complete stopping of the engine incident to such release.